S
M
T
W
T
F
S
30
65°
52°
31
65°
49°
1
66°
51°
2
64°
53°
3
64°
48°
4
65°
47°
5
64°
48°
6
66°
49°
7
67°
50°
8
68°
54°
9
68°
51°
10
63°
53°
11
66°
53°
12
63°
52°
13
67°
53°
14
67°
52°
15
66°
51°
16
64°
49°
17
61°
50°
18
61°
48°
19
64°
46°
20
62°
46°
21
61°
45°
22
61°
46°
23
60°
47°
24
61°
48°
25
60°
51°
26
60°
51°
27
64°
49°
28
63°
47°
29
59°
46°
30
59°
45°
1
60°
44°
2
58°
44°
3
58°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Londonderry
Londonderry's September 2026 forecast shows daily high temperatures ranging from 58° to 68°, with overnight lows between 44° and 54°. The average high for September is 63° with an average low of 49°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Londonderry. See also: October | November | December.
